Communication system based on DOCSIS protocol

ABSTRACT

A communication system based on DOCSIS protocol includes a server, configured to send a signal and demodulate a received signal; a coaxial cable, configured to transmit signals through a coaxial cable network; a frequency divider, configured to divide the signal sent by the server into a downstream signal and a full duplex signal; a downstream communication path, configured to transmit the downstream signal to a first modulation and demodulation unit; an upstream communication path, configured to transmit a upstream signal sent by a second modulation and demodulation unit to the server; a full duplex communication path, configured to simultaneously transmit the downstream signal divided by the frequency divider and the upstream signal, separate the downstream signal from the full duplex signal and transmit to the first modulation and demodulation unit, and transmit the upstream signal sent by the second modulation and demodulation unit to the server.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No.202210453242.0 filed on Apr. 27, 2022, in China National IntellectualProperty Administration, the contents of which are incorporated byreference herein.

FIELD

The present disclosure relates to a field of signal transmission, inparticular to a communication system based on DOCSIS protocol.

BACKGROUND

In the cable network market, with the continuous growth of users' demandfor upstream/downstream network speed, DOCSIS 3.1/3.0/2.0 can no longermeet the needs of users. DOCSIS 4.0 came into being, to provide userswith higher upstream/downstream rate, the upstream bandwidth is expandedfrom 204 MHz to 684 MHz in DOCSIS 4.0. However, such expansion ofbandwidth still cannot meet the current needs of users for networkspeed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a module diagram of an embodiment of the communication system1 based on DOCSIS protocol according to the present disclosure;

FIG. 2 is a module diagram of another embodiment of the communicationsystem 1 based on DOCSIS protocol according to the present disclosure;

FIG. 3 is a schematic diagram of a signal flow direction of the primaryfilter path and the upstream sub communication path according to andembodiment of the present disclosure;

FIG. 4 is a schematic diagram of a signal flow direction of thesecondary filter path and the upstream sub communication path accordingto and embodiment of the present disclosure; and

FIG. 5 is a schematic diagram of a signal flow direction of the tertiaryfilter path and the upstream sub communication path according to andembodiment of the present disclosure.

DETAILED DESCRIPTION

It will be appreciated that for simplicity and clarity of illustration,where appropriate, reference numerals have been repeated among thedifferent figures to indicate corresponding or analogous elements. Inaddition, numerous specific details are set forth in order to provide athorough understanding of the embodiments described herein. However, itwill be understood by those of ordinary skill in the art that theembodiments described herein can be practiced without these specificdetails. In other instances, methods, procedures, and components havenot been described in detail so as not to obscure the related relevantfeature being described. Also, the description is not to be consideredas limiting the scope of the embodiments described herein. The drawingsare not necessarily to scale and the proportions of certain parts havebeen exaggerated to better illustrate details and features of thepresent disclosure. The disclosure is illustrated by way of example andnot by way of limitation in the figures of the accompanying drawings, inwhich like references indicate similar elements. It should be noted thatreferences to “an” or “one” embodiment in this disclosure are notnecessarily to the same embodiment, and such references mean at leastone.

Several definitions that apply throughout this disclosure will now bepresented.

The term “coupled” is defined as connected, whether directly orindirectly through intervening components, and is not necessarilylimited to physical connections. The connection can be such that theobjects are permanently connected or releasably connected. The term“comprising,” when utilized, means “including, but not necessarilylimited to”; it specifically indicates open-ended inclusion ormembership in the so-described combination, group, series, and the like.

Referring to FIG. 1 , FIG. 1 is a module diagram of an embodiment of thecommunication system 1 based on DOCSIS protocol of the presentinvention. In this embodiment, the communication system 1 based onDOCSIS protocol is applicable to DOCSIS 3.1/3.0/2.0 and DOCSIS 4.0,including a server 10, a coaxial cable 20, a frequency divider 30, adownstream communication path 40, a upstream communication path 50, afull duplex communication path 60, a first modulation and demodulationunit 70 and a second modulation and demodulation unit 80.

Specifically, the server 10 is configured to send signals and demodulatereceived signals. The server 10 may be, but is not limited to, a CMTS(cable modem termination system) device. The coaxial cable 20 transmitsthe signals sent and received by the server 10 through a coaxial cablenetwork. In the embodiment, the coaxial cable 20 can be a hybrid fibercoax (HFC). The frequency divider 30 is connected to the coaxial cable20 for dividing the signal sent by the server 10 into a downstreamsignal and a full duplex signal. At the same time, the transmission pathis divided into three transmission paths with different frequency pointsby the frequency divider 30: the downstream communication path 40, theupstream communication path 50 and the full duplex communication path 60to transmit signals at different frequency points. The downstreamcommunication path 40 is configured to transmit the downstream signalsent by the server 10 to the first modulation and demodulation unit 70.The upstream communication path 50 is configured to transmit theupstream signal sent by the second modulation and demodulation unit 80to the server 10. The full duplex communication path 60 is configured tosimultaneously transmit the downstream signal divided by the frequencydivider 30 and the upstream signal sent by the second modulation anddemodulation unit 80, separate the downstream signal from the fullduplex signal and transmit to the first modulation and demodulation unit70, and further transmit the upstream signal sent by the secondmodulation and demodulation unit 80 to the server 10.

In the embodiment, a bandwidth range of the downstream communicationpath 40 is 684 MHz˜1812 MHz, and the downstream communication path 40includes: a first high pass filter HP1, electrically connected betweenthe frequency divider 30 and the first modulation and demodulation unit70 to pass a high-frequency downstream signal with the bandwidth of 684MHz˜1812 MHz, so as to ensure that the downstream signal sent from theCMTS has no attenuation in the bandwidth of 684 MHz˜1812 MHz, reduceparasitic interference outside the band and reduce the signal-to-noiseratio in a signal transmission. A bandwidth range of the upstreamcommunication path 50 is 5 MHz˜85 MHz, and the upstream communicationpath 50 includes a first power amplifier PA1, electrically connected tothe second modulation and demodulation unit 80 for adjusting a power ofthe upstream signal sent by the second modulation and demodulation unit80; a system-on-a-chip SoC, electrically connected to the first poweramplifier for controlling a magnification of the first power amplifierPA1; a first low-pass filter LP1, electrically connected between thefirst power amplifier PA1 and the frequency divider 30 for passing thelow-frequency upstream signal with the bandwidth of 5 MHz˜85 MHz, so asto ensure that the upstream signal sent by the second modulation anddemodulation unit 80 has no attenuation in the bandwidth of 5 MHz˜85MHz, reduce the parasitic interference outside the band and reduce thesignal-to-noise ratio of signal transmission.

As shown in FIG. 2 , FIG. 2 is a module diagram of another embodiment ofthe communication system 1 based on DOCSIS protocol of the presentdisclosure. In the embodiment, the communication system 1 based onDOCSIS protocol is applicable to DOCSIS3.1/3.0/2.0 and DOCSIS4.0,including a server 10, a coaxial cable 20, a frequency divider 30, adownstream communication path 40, a upstream communication path 50, afull duplex communication path 60, a first modulation and demodulationunit 70 and a second modulation and demodulation unit 80. The workingprinciple of the server 10, the coaxial cable 20, the frequency divider30, the downstream communication path 40, the upstream communicationpath 50, the first modulation and demodulation unit 70 and the secondmodulation and demodulation unit 80 is similar to the above embodiment,will not be repeated here.

In the embodiment, the full duplex communication path 60 performs signalseparation on the full-duplex signal, and separates the downstreamsignal therefrom. In-band stepped (three-stage filter path) filterdesign reduces the harmonic interference of each frequency band is used,which is to ensure signal integrity and reliability. Specifically, asshown in FIG. 2 , the full duplex communication path 60 includes aprimary filter path 601, a secondary filter path 602, a tertiary filterpath 603 and an upstream sub communication path 604. A bandwidth rangeof full duplex communication path 60 is 108 MHz˜684 MHz. The secondmodulation and demodulation unit 80 is electrically connected to thefrequency divider 30 to form the upstream sub communication path 604 totransmit the upstream signal sent by the second modulation anddemodulation unit 80 to the server 10.

In the embodiment, the primary filtering path 601 includes: a secondlow-pass filter LP2, electrically connected to the frequency divider 30or passing downstream signals with the bandwidth of 108 MHz˜684 MHz; afirst synthesizer SY1, a first input end of the first synthesizer SY1 iselectrically connected to an output of the second low-pass filter LP2for removing the upstream signal in the full duplex signal leading tothe first modulation and demodulation unit 70; a first RF switch SW1, acommon end of the first RF switch SW1 is electrically connected to anoutput end of the first synthesizer SY1, and a first end of the first RFswitch SW1 is electrically connected to the first modulation anddemodulation unit 70 for transmitting the downstream signal with thebandwidth of 108 MHz˜684 MHz to the first modulation and demodulationunit 70; a first phase regulator PR1, an input end of the first phaseregulator PR1 is electrically connected to the second modulation anddemodulation unit 80 for phase adjustment of the upstream signal sent bythe second modulation and demodulation unit 80; a second power amplifierPA2, an input end of the second power amplifier PA2 is electricallyconnected to an output end of the first phase regulator PR1, and anoutput end of the second power amplifier is electrically connected to asecond input end of the first synthesizer SY1 for adjusting a power ofthe phase adjusted signal and outputting a signal with the oppositephase and the same power as the upstream signal sent by the secondmodulation and demodulation unit 80; the system-on-a-chip SoC,electrically connected to the second power amplifier PA2 for controllinga magnification of the second power amplifier PA2.

Combined with FIG. 3 , FIG. 3 is a schematic diagram of a signal flowdirection of the primary filter path 601 and the upstream subcommunication path 604. As shown in FIG. 3 , the full duplex signaldivided by the frequency divider 30 is transmitted to the firstmodulation and demodulation unit 70 through the second low-pass filterLP2, the first synthesizer SY1 and the first end of the first RF switchSW1. The upstream signal sent by the second modulation and demodulationunit 80 is divided into two channels. One channel is transmitted to theserver 10 through the upstream sub communication path 604, and the otherchannel enters the first modulation and demodulation unit 70 through thefirst synthesizer SY1 and the first end of the first RF switch SW1 afterbeing adjusted by the first phase regulator PR1 and the second poweramplifier PA2.

In the embodiment, the secondary filtering path includes: the secondlow-pass filter LP2, the input end of the second low-pass filter LP2 iselectrically connected to the frequency divider 30 for passing thedownstream signal with a bandwidth of 108 MHz˜684 MHz; the firstsynthesizer SY1, the first input of the first synthesizer SY1 iselectrically connected to the output of the second low-pass filter LP2;the first RF switch SW1, the common end of the first RF switch SW1 iselectrically connected to the output end of the first synthesizer SY1; athird low-pass filter LP3, an input end of the third low-pass filter LP3is electrically connected to a second end of the first RF switch SW1 forpassing the downstream signal with a bandwidth of 108 MHz˜492 MHz; asecond synthesizer SY2, a first input end of the second synthesizer SY2is electrically connected to an output of the third low-pass filter LP3;a second RF switch SW2, a common end of the second RF switch SW2 iselectrically connected to an output end of the second synthesizer SY2,and a first end of the second RF switch SW2 is electrically connected tothe first modulation and demodulation unit for transmitting thedownstream signal with the bandwidth of 108 MHz˜492 MHz to the firstmodulation and demodulation unit 70; a second phase regulator PR2, aninput end of the second phase regulator PR2 is electrically connected tothe second modulation and demodulation unit 80 for phase adjustment ofthe upstream signal sent by the second modulation and demodulation unit80; a third power amplifier PA3, an input end of the third poweramplifier PA3 is electrically connected to an output end of the secondphase regulator PR2, and an output end of the third power amplifier iselectrically connected to a second input end of the second synthesizerSY2, for adjusting a power of the phase adjusted signal and output asignal with the opposite phase and the same power as the upstream signalsent by the second modulation and demodulation unit 80; thesystem-on-a-chip SoC, electrically connected to the third poweramplifier PA3, for controlling a magnification of the third poweramplifier PA3.

Combined with FIG. 4 , FIG. 4 is a schematic diagram of a signal flowdirection of the secondary filter path 602 and the upstream subcommunication path 604. As shown in FIG. 4 , the full duplex signaldivided by the frequency divider 30 is transmitted to the firstmodulation and demodulation unit 70 through the second low-pass filterLP2, the first synthesizer SY1, the second end of the first RF switchSW1, the third low-pass filter LP3, the second synthesizer SY2 and thefirst end of the second RF switch SW2. At this time, there is no signalinput to the second input end of the first synthesizer SY1, and thesignals at the first input end and the output end of the firstsynthesizer SY1 are consistent without any signal processing. Theupstream signal sent by the second modulation and demodulation unit 80is divided into two channels. One channel is transmitted to the server10 through the upstream sub communication path 604, and the otherchannel enters the first modulation and demodulation unit 70 through thefirst end of the second synthesizer SY2 and the second RF switch SW1after being adjusted by the second phase regulator PR2 and the thirdpower amplifier PA3.

In the embodiment, the tertiary filter path includes: the secondlow-pass filter LP2, the input end of the second low-pass filter LP2 iselectrically connected to the frequency divider 30 or passing thedownstream signal with a bandwidth of 108 MHz˜684 MHz; the firstsynthesizer SY1, the first input of the first synthesizer SY1 iselectrically connected to the output end of the second low-pass filterLP2; the first RF switch SW1, the common end of the first RF switch SW1is electrically connected to the output end of the first synthesizerSY1; the third low-pass filter LP3, the input end of the third low-passfilter LP3 is electrically connected to the second end of the first RFswitch SW1 for passing the downstream signal with a bandwidth of 108MHz˜492 MHz; the second synthesizer SY2, the first input end of thesecond synthesizer SY2 is electrically connected to the output end ofthe third low-pass filter LP3; the second RF switch SW2, the common endof the second RF switch SW2 is electrically connected to the output endof the second synthesizer SY2; a fourth low-pass filter LP4, an inputend of the fourth low-pass filter LP4 is electrically connected to asecond end of the second RF switch SW2; a third synthesizer SY3, a firstinput end of the third synthesizer SY3 is electrically connected to anoutput end of the fourth low-pass filter LP4, and an output of the thirdsynthesizer SY3 is electrically connected to the first modulation anddemodulation unit 70 for transmitting the downstream signal with thebandwidth of 108 MHz˜300 MHz to the first modulation and demodulationunit 70; a third phase regulator PR3, an input end of the third phaseregulator PR3 is electrically connected to the second modulation anddemodulation unit 80 for phase adjustment of the upstream signal sent bythe second modulation and demodulation unit 80; a fourth power amplifierPA4, an input end of the fourth power amplifier PA4 is electricallyconnected to an output end of the third phase regulator PR3, and theoutput end of the fourth power amplifier PA4 is electrically connectedto the second input end of the third synthesizer SY3, for adjusting apower of the phase adjusted signal and output a signal with the oppositephase and the same power as the upstream signal sent by the secondmodulation and demodulation unit 80; the system-on-a-chip SoC,electrically connected to the fourth power amplifier PA4, forcontrolling a magnification of the fourth power amplifier PA4.

Combined with FIG. 5 , FIG. 5 is a schematic diagram of a signal flowdirection of the tertiary filter path 603 and the upstream subcommunication path 604. As shown in FIG. 5 , the full duplex signaldivided by the frequency divider 30 passes through the second low-passfilter LP2, the first synthesizer SY1, the second end of the first RFswitch SW1, the third low-pass filter LP3, the second synthesizer SY2,the second end of the second RF switch SW2, the fourth low-pass filterLP4 and the third synthesizer SY3 to transmit to the first modulationand demodulation unit 70. At this time, there is no signal input to thesecond input of the second synthesizer SY2, and the signals at the firstinput end and the output end of the second synthesizer SY2 areconsistent without any signal processing. The upstream signal sent bythe second modulation and demodulation unit 80 is divided into twochannels. One channel is transmitted to the server 10 through theupstream sub communication path 604, and the other channel enters thefirst modulation and demodulation unit 70 through the third synthesizersy3 after being adjusted by the third phase regulator PR3 and the fourthpower amplifier PA4. The upstream and downstream are multiplexed withinthe bandwidth of 108 MHz˜684 MHz to improve the upstream and downstreamtransmission speed.

The communication system 1 based on DOCSIS protocol provided by theinvention is applicable to DOCSIS3.1/3.0/2.0 and DOCSIS4.0. When thecommunication protocol is DOCSIS3.1/3.0/2.0, the common end of the firstRF switch SW1 is connected to the first end, and the second poweramplifier PA2, the third power amplifier PA3 and the fourth poweramplifier PA4 have no signal output. When the communication protocol isDOCSIS4.0: when the bandwidth range of the downstream signal is a firstbandwidth range: 108 MHz˜300 MHz, the common end of the first RF switchSW1 is connected to the second end, and the common end of the second RFswitch SW2 is connected to the second end; when the bandwidth range ofthe downstream signal is a second bandwidth range: 300 MHz˜492 MHz, thecommon end of the first RF switch SW1 is connected to the second end,and the common end of the second RF switch SW2 is connected to the firstend; when the bandwidth range of the downstream signal is a thirdbandwidth range of 492 MHz˜684 MHz, the common end of the first RFswitch SW1 is connected to the first end.

In a process of signal transmission, the transmission path will causesignal loss, so it is necessary to compensate the damaged signal.Specifically, the second modulation and demodulation unit 80 is furtherconfigured to send out calibration signals with the first bandwidthrange, the second bandwidth range and the third bandwidth range. Whenthe second modulation and demodulation unit 80 sends out the calibrationsignal with the first bandwidth range, the calibration signal reachesthe first modulation and demodulation unit 70 through the upstream subcommunication path 604 and the tertiary filter path 603, and thesystem-on-a-chip SoC adjusts the fourth power amplifier PA4 and thethird phase regulator PR3 to cause the power of the calibration signalwith the first bandwidth range obtained by the first modulation anddemodulation unit 70 to become 0 dbmv. The system-on-a-chip SoC isfurther configured to record relevant parameters of the fourth poweramplifier PA4 and the third phase regulator PR3 at this time.

When the second modulation and demodulation unit 80 sends out thecalibration signal with the second bandwidth range, the calibrationsignal reaches the first modulation and demodulation unit 70 through theupstream sub communication path 604 and the secondary filter path 603,and the system-on-a-chip SoC adjusts the third power amplifier PA3 andthe second phase regulator PR2 to cause the power obtained by thecalibration signal of the second bandwidth range in the first modulationand demodulation unit 70 to become 0 dbmv. The system-on-a-chip SoC isfurther configured to record relevant parameters of the third poweramplifier PA3 and the second phase regulator PR2 at this time.

When the second modulation and demodulation unit 80 sends out thecalibration signal with the third bandwidth range, the calibrationsignal reaches the first modulation and demodulation unit 70 through theupstream sub communication path 604 and the primary filter path 603, andthe system-on-a-chip SoC adjusts the second power amplifier PA2 and thefirst phase regulator PR1 to cause the power obtained by the calibrationsignal of the third bandwidth range in the first modulation anddemodulation unit 70 to become 0 dbmv. The system-on-a-chip SoC isfurther configured to record relevant parameters of the second poweramplifier PA2 and the first phase regulator PR1 at this time.

Compared with the prior art, the communication system based on DOCSISprotocol provided by the embodiment of the present disclosure sendssignals through the server and demodulates the received signals; signalssent and received by the server is transmitted through the coaxialcable; Then, the signal sent by the server is divided into downstreamsignal and full duplex signal by the frequency divider; further, thedownstream signal sent by the server is transmitted to the firstmodulation and demodulation unit through the downstream communicationpath, the upstream communication path transmits the upstream signal sentby the second modulation and demodulation unit to the server, and thefull duplex communication path simultaneously transmits the downstreamsignal divided by the frequency divider and the upstream signal sent bythe second modulation and demodulation unit, separates the downstreamsignal from the full duplex signal and transmit to the first modulationand demodulation unit, and transmits the upstream signal sent by thesecond modulation and demodulation unit to the server, so as to realizeupstream and downstream in band multiplexing and improve the upstreamand downstream transmission speed.

Many details are often found in the art such as the other features of amobile terminal. Therefore, many such details are neither shown nordescribed. Even though numerous characteristics and advantages of thepresent technology have been set forth in the foregoing description,together with details of the structure and function of the presentdisclosure, the disclosure is illustrative only, and changes may be madein the detail, especially in matters of shape, size, and arrangement ofthe parts within the principles of the present disclosure, up to andincluding the full extent established by the broad general meaning ofthe terms used in the claims. It will therefore be appreciated that theembodiments described above may be modified within the scope of theclaims.

What is claimed is:
 1. A communication system based on Data Over CableService Interface Specification (DOCSIS) protocol, the communicationsystem comprising: a server configured to send a signal and demodulate areceived signal; a coaxial cable configured to transmit signals sent andreceived by the server through a coaxial cable network; a frequencydivider connected to the coaxial cable, and configured to divide thesignal sent by the server into a downstream signal and a full duplexsignal; a downstream communication path configured to transmit thedownstream signal sent by the server to a first modulation anddemodulation unit; an upstream communication path configured to transmitan upstream signal sent by a second modulation and demodulation unit tothe server; and a full duplex communication path configured tosimultaneously transmit the downstream signal divided by the frequencydivider and the upstream signal sent by the second modulation anddemodulation unit, separate the downstream signal from the full duplexsignal and transmit to the first modulation and demodulation unit, andtransmit the upstream signal sent by the second modulation anddemodulation unit to the server; wherein a bandwidth range of the fullduplex communication path is 108 Mega Hertz (MHz)˜684 MHz, and the fullduplex communication path comprises a primary filter path, a secondaryfilter path and a tertiary filter path: the primary filtering pathcomprises: a second low-pass filter electrically connected to thefrequency divider, and configured for passing downstream signals with abandwidth of 108 MHz˜684 MHz; a first synthesizer, a first input end ofthe first synthesizer being electrically connected to an output of thesecond low-pass filter, the first synthesizer being configured forremoving the upstream signal in the full duplex signal leading to thefirst modulation and demodulation unit; a first Radio Frequency (RF)switch, a common end of the first RF switch being electrically connectedto an output end of the first synthesizer, a first end of the first RFswitch being electrically connected to the first modulation anddemodulation unit, the first RF switch being configured for transmittingthe downstream signal with the bandwidth of 108 MHz˜684 MHz to the firstmodulation and demodulation unit; a first phase regulator, an input endof the first phase regulator being electrically connected to the secondmodulation and demodulation unit, the first phase regulator beingconfigured for phase adjustment of the upstream signal sent by thesecond modulation and demodulation unit; a second power amplifier, aninput end of the second power amplifier being electrically connected toan output end of the first phase regulator, an output end of the secondpower amplifier being electrically connected to a second input end ofthe first synthesizer, the second power amplified being configured foradjusting a power of the phase adjusted signal and outputting a signalwith an opposite phase and a same power as the upstream signal sent bythe second modulation and demodulation unit; a system-on-a-chipelectrically connected to the second power amplifier, and configured forcontrolling a magnification of the second power amplifier.
 2. Thecommunication system based on DOCSIS protocol according to claim 1,wherein a bandwidth range of the downstream communication path is 684Mega Hertz (MHz)˜1812 MHz, and the downstream communication pathcomprises: a first high pass filter electrically connected between thefrequency divider and the first modulation and demodulation unit to passa high-frequency downstream signal with the bandwidth of 684 MHz˜1812MHz.
 3. The communication system based on DOCSIS protocol according toclaim 1, wherein a bandwidth range of the upstream communication path is5 MHz˜85 MHz, and the upstream communication path comprises: a firstpower amplifier electrically connected to the second modulation anddemodulation unit, and configured for adjusting a power of the upstreamsignal sent by the second modulation and demodulation unit; asystem-on-a-chip electrically connected to the first power amplifier,and configured for controlling a magnification of the first poweramplifier; a first low-pass filter electrically connected between thefirst power amplifier and the frequency divider, and configured forpassing a low-frequency upstream signal with a bandwidth of 5 MHz˜85MHz.
 4. The communication system based on DOCSIS protocol according toclaim 1, wherein the secondary filtering path comprises: the secondlow-pass filter, the input end of the second low-pass filter beingelectrically connected to the frequency divider, the second low-passfilter being configured for passing the downstream signal with abandwidth of 108 MHz˜684 MHz; the first synthesizer, the first input ofthe first synthesizer being electrically connected to the output of thesecond low-pass filter; the first RF switch, the common end of the firstRF switch being electrically connected to the output end of the firstsynthesizer; a third low-pass filter, an input end of the third low-passfilter being electrically connected to a second end of the first RFswitch, the third low-pass filter being configured for passing thedownstream signal with a bandwidth of 108 MHz˜492 MHz; a secondsynthesizer, a first input end of the second synthesizer beingelectrically connected to an output of the third low-pass filter; asecond RF switch, a common end of the second RF switch beingelectrically connected to an output end of the second synthesizer, afirst end of the second RF switch being electrically connected to thefirst modulation and demodulation unit, the second RF switch beingconfigured for transmitting the downstream signal with the bandwidth of108 MHz˜492 MHz to the first modulation and demodulation unit; a secondphase regulator, an input end of the second phase regulator beingelectrically connected to the second modulation and demodulation unit,the second phase regular being configured for phase adjustment of theupstream signal sent by the second modulation and demodulation unit; athird power amplifier, an input end of the third power amplifier beingelectrically connected to an output end of the second phase regulator,an output end of the third power amplifier being electrically connectedto a second input end of the second synthesizer, the third poweramplifier being configured for adjusting a power of the phase adjustedsignal and output a signal with an opposite phase and a same power asthe upstream signal sent by the second modulation and demodulation unit;the system-on-a-chip, electrically connected to the third poweramplifier, and configured for controlling a magnification of the thirdpower amplifier.
 5. The communication system based on DOCSIS protocolaccording to claim 4, wherein the tertiary filter path comprises: thesecond low-pass filter, the input end of the second low-pass filterbeing electrically connected to the frequency divider, and configuredfor passing the downstream signal with a bandwidth of 108 MHz˜684 MHz;the first synthesizer, the first input of the first synthesizer beingelectrically connected to the output end of the second low-pass filter;the first RF switch, the common end of the first RF switch beingelectrically connected to the output end of the first synthesizer; thethird low-pass filter, the input end of the third low-pass filter beingelectrically connected to the second end of the first RF switch, thethird low-pass filter being configured for passing the downstream signalwith a bandwidth of 108 MHz˜492 MHz; the second synthesizer, the firstinput end of the second synthesizer being electrically connected to theoutput end of the third low-pass filter; the second RF switch, thecommon end of the second RF switch being electrically connected to theoutput end of the second synthesizer; a fourth low-pass filter, an inputend of the fourth low-pass filter being electrically connected to asecond end of the second RF switch; a third synthesizer, a first inputend of the third synthesizer being electrically connected to an outputend of the fourth low-pass filter, an output of the third synthesizerbeing electrically connected to the first modulation and demodulationunit, the third synthesizer being configure for transmitting thedownstream signal with the bandwidth of 108 MHz˜300 MHz to the firstmodulation and demodulation unit; a third phase regulator, an input endof the third phase regulator being electrically connected to the secondmodulation and demodulation unit, the third phase regulator beingconfigured for phase adjustment of the upstream signal sent by thesecond modulation and demodulation unit; a fourth power amplifier, aninput end of the fourth power amplifier being electrically connected toan output end of the third phase regulator, and the output end of thefourth power amplifier being electrically connected to the second inputend of the third synthesizer, the fourth power amplifier beingconfigured for adjusting a power of the phase adjusted signal and outputa signal with an opposite phase and a same power as the upstream signalsent by the second modulation and demodulation unit; thesystem-on-a-chip, electrically connected to the fourth power amplifier,and configured for controlling a magnification of the fourth poweramplifier.
 6. The communication system based on DOCSIS protocolaccording to claim 5, wherein the second modulation and demodulationunit is further electrically connected to a common end of the frequencydivider and the second low-pass filter to form an upstream subcommunication path to transmit the upstream signal sent by the secondmodulation and demodulation unit to the server.
 7. The communicationsystem based on DOCSIS protocol according to claim 6, wherein when thecommunication protocol is DOCSIS4.0: when the bandwidth range of thedownstream signal is a first bandwidth range ranging from 108 MHz to 300MHz, the common end of the first RF switch is connected to the secondend of the first RF switch, and the common end of the second RF switchis connected to the second end of the second RF switch; when thebandwidth range of the downstream signal is a second bandwidth rangeranging from 300 MHz to 492 MHz, the common end of the first RF switchis connected to the second end of the first RF switch, and the commonend of the second RF switch is connected to the first end of the secondRF switch; when the bandwidth range of the downstream signal is a thirdbandwidth range ranging from 492 MHz to 684 MHz, the common end of thefirst RF switch is connected to the first end.
 8. The communicationsystem based on DOCSIS protocol according to claim 6, when thecommunication protocol is DOCSIS3.1/3.0/2.0: the common end of the firstRF switch is connected to the first end of the first RF switch, and thesecond power amplifier, the third power amplifier and the fourth poweramplifier have no signal output.
 9. The communication system based onDOCSIS protocol according to claim 6, wherein: the second modulation anddemodulation unit is further configured to send out calibration signalswith a first bandwidth range, a second bandwidth range and a thirdbandwidth range; when the second modulation and demodulation unit sendsout the calibration signal with the first bandwidth range, thecalibration signal reaches the first modulation and demodulation unitthrough the upstream sub communication path and the tertiary filterpath, and the system-on-a-chip adjusts the fourth power amplifier andthe third phase regulator to cause a power of the calibration signalwith the first bandwidth range obtained by the first modulation anddemodulation unit to become 0 Decimal Bel Millivolt (dbmv); when thesecond modulation and demodulation unit sends out the calibration signalwith the second bandwidth range, the calibration signal reaches thefirst modulation and demodulation unit through the upstream subcommunication path and the secondary filter path, and thesystem-on-a-chip adjusts the third power amplifier and the second phaseregulator to cause the power obtained by the calibration signal of thesecond bandwidth range in the first modulation and demodulation unit tobecome 0 dbmv; when the second modulation and demodulation unit sendsout the calibration signal with the third bandwidth range, thecalibration signal reaches the first modulation and demodulation unitthrough the upstream sub communication path and the primary filter path,and the system-on-a-chip adjusts the second power amplifier and thefirst phase regulator to cause the power obtained by the calibrationsignal of the third bandwidth range in the first modulation anddemodulation unit to become 0 dbmv.